core/mixer.h

   1 #ifndef CORE_MIXER_H
   2 #define CORE_MIXER_H
   3
   4 #include <array>
   5 #include <cmath>
   6 #include <cstddef>
   7
   8 #include "alspan.h"
   9 #include "ambidefs.h"
  10 #include "bufferline.h"
  11
  12 struct MixParams;
  13
  14 /* Mixer functions that handle one input and multiple output channels. */
  15 using MixerOutFunc = void(*)(const al::span<const float> InSamples,
  16     const al::span<FloatBufferLine> OutBuffer, const al::span<float> CurrentGains,
  17     const al::span<const float> TargetGains, const std::size_t Counter, const std::size_t OutPos);
  18
  19 extern MixerOutFunc MixSamplesOut;
  20 inline void MixSamples(const al::span<const float> InSamples,
  21     const al::span<FloatBufferLine> OutBuffer, const al::span<float> CurrentGains,
  22     const al::span<const float> TargetGains, const std::size_t Counter, const std::size_t OutPos)
  23 { MixSamplesOut(InSamples, OutBuffer, CurrentGains, TargetGains, Counter, OutPos); }
  24
  25 /* Mixer functions that handle one input and one output channel. */
  26 using MixerOneFunc = void(*)(const al::span<const float> InSamples,const al::span<float> OutBuffer,
  27     float &CurrentGain, const float TargetGain, const std::size_t Counter);
  28
  29 extern MixerOneFunc MixSamplesOne;
  30 inline void MixSamples(const al::span<const float> InSamples, const al::span<float> OutBuffer,
  31     float &CurrentGain, const float TargetGain, const std::size_t Counter)
  32 { MixSamplesOne(InSamples, OutBuffer, CurrentGain, TargetGain, Counter); }
  33
  34
  35 /**
  36  * Calculates ambisonic encoder coefficients using the X, Y, and Z direction
  37  * components, which must represent a normalized (unit length) vector, and the
  38  * spread is the angular width of the sound (0...tau).
  39  *
  40  * NOTE: The components use ambisonic coordinates. As a result:
  41  *
  42  * Ambisonic Y = OpenAL -X
  43  * Ambisonic Z = OpenAL Y
  44  * Ambisonic X = OpenAL -Z
  45  *
  46  * The components are ordered such that OpenAL's X, Y, and Z are the first,
  47  * second, and third parameters respectively -- simply negate X and Z.
  48  */
  49 std::array<float,MaxAmbiChannels> CalcAmbiCoeffs(const float y, const float z, const float x,
  50     const float spread);
  51
  52 /**
  53  * CalcDirectionCoeffs
  54  *
  55  * Calculates ambisonic coefficients based on an OpenAL direction vector. The
  56  * vector must be normalized (unit length), and the spread is the angular width
  57  * of the sound (0...tau).
  58  */
  59 inline std::array<float,MaxAmbiChannels> CalcDirectionCoeffs(const al::span<const float,3> dir,
  60     const float spread)
  61 {
  62     /* Convert from OpenAL coords to Ambisonics. */
  63     return CalcAmbiCoeffs(-dir[0], dir[1], -dir[2], spread);
  64 }
  65
  66 /**
  67  * CalcDirectionCoeffs
  68  *
  69  * Calculates ambisonic coefficients based on an OpenAL direction vector. The
  70  * vector must be normalized (unit length).
  71  */
  72 constexpr std::array<float,MaxAmbiChannels> CalcDirectionCoeffs(const al::span<const float,3> dir)
  73 {
  74     /* Convert from OpenAL coords to Ambisonics. */
  75     return CalcAmbiCoeffs(-dir[0], dir[1], -dir[2]);
  76 }
  77
  78 /**
  79  * CalcAngleCoeffs
  80  *
  81  * Calculates ambisonic coefficients based on azimuth and elevation. The
  82  * azimuth and elevation parameters are in radians, going right and up
  83  * respectively.
  84  */
  85 inline std::array<float,MaxAmbiChannels> CalcAngleCoeffs(const float azimuth,
  86     const float elevation, const float spread)
  87 {
  88     const float x{-std::sin(azimuth) * std::cos(elevation)};
  89     const float y{ std::sin(elevation)};
  90     const float z{ std::cos(azimuth) * std::cos(elevation)};
  91
  92     return CalcAmbiCoeffs(x, y, z, spread);
  93 }
  94
  95
  96 /**
  97  * ComputePanGains
  98  *
  99  * Computes panning gains using the given channel decoder coefficients and the
 100  * pre-calculated direction or angle coefficients. For B-Format sources, the
 101  * coeffs are a 'slice' of a transform matrix for the input channel, used to
 102  * scale and orient the sound samples.
 103  */
 104 void ComputePanGains(const MixParams *mix, const al::span<const float,MaxAmbiChannels> coeffs,
 105     const float ingain, const al::span<float,MaxAmbiChannels> gains);
 106
 107 #endif /* CORE_MIXER_H */